Native Threading With A Linux JDK?

mikej asks: "I've always had issues with the native threading of Sun's JDKs on Linux, but have been able to get around the problems by using green threads. I've come into a situation where I absolutely must use native threads, and the Blackdown-derived 1.3 [J/S]DK from Sun simply doesn't cut it (context switing time, which is a Linux issue, is part of the problem as well). Is there a reliable (and reasonably quick) native-threading JDK available for Linux? I much prefer a Free or Open Source version, but if I have to start using commercial software to get this functionality then I have no choice. In addition, are there different Linux threading libraries available?"